Greene brothers' clinical course in dental prosthesis : in three printed lectures; new and advance-test methods in impression, articulation, occlusion, roofless dentures, refits and renewals / by Jacob W. Greene.

  • Greene, Jacob W. (Jacob Wesley), 1839-1916.
Date:
[1914]
Catalogue details

Licence: Public Domain Mark

Credit: Greene brothers' clinical course in dental prosthesis : in three printed lectures; new and advance-test methods in impression, articulation, occlusion, roofless dentures, refits and renewals / by Jacob W. Greene. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    we cease the pressure, and will lift the impres- sion (or plate) off the hard parts; in which case there would be air under it, over the hard parts. And, of course, the air there would, to some extent, offset and neutralize the air pressure from the opposite (upper) side. In other words, our suction (atmospheric weight) would be lessened. But, on the other hand, if we press too light- ly on the soft parts and don't make them give any at all, the impression (or plate) will rest so loosely on them as to admit of air there; and again we 'd have lessened atmospheric pressure. Atmosplieric pressure and suction are syn- onymous terms. Whenever there is any air un- der a plate, however rarefied it may be, the sticktion will be lessened accordingly. So, when you don't press the soft parts up with enough strain, you say your plate rests too hard on the hard places. This isn't ex- actly true—only relatively true, since the bear- ing is correct on the hard parts, and lacking elsewhere. Perfect adaptation means a similar strain on the hard and soft places; but atmospheric pressure, or suction, is what holds an upper plate to its place—unless clasps or other clap* trap means are used. I '11 merely remark here, a little premature- ly, that I '11 show you later on in this lesson that it takes surprisingly little suction to hold a plate u]) if it has no strain to throw it loose. But ecpialized strain on the hard and soft parts isn't all, nor even the most important thing, to be obtained in this matter. We have movable parts—muscles and tissues—that must be accommodated, as vou here see on and around
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